fix json in yml

compose-files/aquarius.yml

@@ -32,6 +32,7 @@ services:
       RUN_EVENTS_MONITOR: "1"
       AQUARIUS_URL: http://172.15.0.5:5000
       EVENTS_MONITOR_SLEEP_TIME: ${EVENTS_MONITOR_SLEEP_TIME}
-      SUBGRAPH_URLS: '{"8996": "http://172.15.0.15:8000"}'
+      SUBGRAPH_URLS: |
+              {"8996": "http://172.15.0.15:8000"}
     volumes:
     - ${OCEAN_ARTIFACTS_FOLDER}:/ocean-contracts/artifacts/